Semiconductor image sensors are used for sensing light. Complementary metal-oxide-semiconductor (CMOS) image sensors (CIS) and charge-coupled device (CCD) sensors are widely used in various applications such as digital still camera or mobile phone camera applications.
The image sensor device can be categorized into two types. A front-side illuminated (FSI) type sensor receives incident light from an active surface (front side) of the substrate while a back-side illuminated (BSI) type sensor receives light from a backside of the substrate. The image sensor device is design to transform received light into electrical signals. However, as the component size of image sensors shrinks along with improvements in manufacturing technologies, existing image sensor devices may suffer from performance issues such as electrical or optical crosstalk. As a result, improved image sensor designs are in need.